The present invention relates in general to defibrillators and defibrillator trainers, particularly defibrillators capable of delivering multiple therapies to a patient. More specifically, the invention relates to defibrillators capable of delivering asynchronous and synchronous defibrillation therapy. The defibrillators of the invention are manual defibrillators, but could also include automatic or semi-automatic external defibrillators (AEDs) provided it is capable of delivering multiple therapies or at least synchronous and asynchronous defibrillation therapy. In particular, this invention relates to a method for distinguishing between asynchronous and synchronous therapy modes in a defibrillator as well as a defibrillator that operates according to the method.
Sudden cardiac death is the leading cause of death in the United States, with one person dying every two minutes. Most sudden cardiac death is caused by ventricular fibrillation (xe2x80x9cVFxe2x80x9d), in which the heart""s muscle fibers contract without coordination, thereby interrupting normal blood flow to the body. When VF occurs, the patient loses consciousness as a result of the interruption in blood flow. The only known effective treatment for VF is electrical defibrillation, in which an electrical pulse is applied to the patient""s heart. The electrical pulse must be delivered within a short time after onset of VF in order for the patient to have any reasonable chance of survival. Electrical defibrillation may also be used to treat shockable ventricular tachycardia (xe2x80x9cVTxe2x80x9d). Accordingly, defibrillation is the appropriate therapy for any shockable rhythm, i.e., VF or shockable VT. In delivering defibrillation therapy to treat VF or shockable VT, because the cardiac rhythm is disorganized, delivery of therapy is not synchronized to the cardiac rhythm.
Atrial fibrillation (xe2x80x9cAFxe2x80x9d) is a commonly occurring cardiac arrhythmia. During AF the atria of the heart is in fibrillation, but the ventricles continue to pump properly. Although the patient is conscious, AF is still a significant health risk because, if left untreated, AF can result in stroke. AF is treated by delivering a synchronized defibrillation energy pulse to the patient. The energy pulse is synchronized with the R wave of the QRS complex of the electrocardiogram (xe2x80x9cECGxe2x80x9d) of the heart, where the QRS complex represents activation of the ventricles. Failure to deliver the energy at the appropriate time during the QRS complex could result in VF. Further information on treatment of Cardiac Arrhythmias can be obtained in Emergency Cardiac Care Committee, et al., xe2x80x9cIII. Adult Advanced Cardiac Life Supportxe2x80x9d JAMA 268:2172-2183 (1992). See also, Marriott""s Practical Electrocardiography, 9th Ed. (Galen Wagner).
Because of these two different therapy modes, defibrillators typically include a mode for delivering therapy to treat VF (using an unsynchronized defibrillation energy), and to treat AF (using a synchronized defibrillation energy also referred to as xe2x80x9csynchronized cardioversionxe2x80x9d). Additionally, these devices may also be capable of pacing and monitoring. Importantly, when treating a cardiac emergency, a caregiver must not deliver a synchronized shock when an unsynchronized shock is required or vise versa. If a synchronized shock is attempted to treat VF, no therapy will be delivered since the cardiac signal is chaotic and the defibrillator will not detect an R-wave from which to synchronize delivery of the energy pulse. Conversely, if an unsynchronized shock is delivered to a patient suffering from AF, the patient will likely go into VF, thus causing a serious.
One drawback to currently available defibrillators capable of delivering multiple therapies, such as synchronized and unsynchronized shocks, is that the caregiver must look at the device to determine the current treatment mode. For safety reasons, the device is checked before each use as well as during use. Further, once therapy has begun there is no way for the caregiver to confirm the correct treatment mode without returning to the device settings.
What is needed, therefore, is a way for the defibrillator to automatically provide confirmation of the treatment mode to the user when the device is in use without requiring the user to review the device settings.
A method of advising a user of a current therapy mode setting of a defibrillator comprising: deploying the defibrillator, the defibrillator having a controller, an energy delivery system operable by the controller to deliver an electrical shock from an energy source to an electrode interface, and an audible prompt generator, wherein the defibrillator is attached to a patient; detecting input from the user; delivering an audible prompt to the user confirming the current therapy mode setting of the defibrillator; and delivering therapy to a patient in the selected therapy mode. The step of delivering a prompt to the user can be performed when the defibrillator is charging the energy source, when the energy source is charged, when the defibrillator delivering therapy to the patient, or at a plurality of times. These prompts can be tonal prompts or verbal prompts. Tonal prompts typically would be either high frequency tones or low frequency tones.
An external defibrillator comprising: a controller, an energy delivery system operable by the controller to deliver an electrical shock from an energy source to an electrode interface in a plurality of treatment modes; and an audible prompt generator to deliver an audible prompt indicative of a current therapy mode to the user. The audible prompt generator generates tonal prompts or verbal prompts. Tonal prompts can be either high frequency tones or low frequency tones. The prompts are delivered by the defibrillator to the user when the defibrillator is charging the energy source, when the energy source is charged, when the defibrillator delivering therapy to the patient, or at a plurality of times.
Thus, it is an object of the present invention to provide medical personnel and caregivers with a defibrillator that automatically confirms the operation mode of the device during therapy.
It is a further object of the invention to provide a defibrillator that generates an audible prompt to the user of the operation mode. This audible prompt may be either tonal or verbal and may occur during charge, at charge done or at shock delivery.